I've bought some flies off eBay for bones and stripers and some of them were ok, but some fell apart without ever using them, just from handling. It's hit or miss and you'll have a hard time telling from the auction pictures how good the flies are.
The flies that fell apart weren't complicated patterns either, just some clousers, and those aren't exactly hard to tie. Those purchases were in my pre-tying days and I don't think I'd buy flies off eBay again. I think you're much better off going to your local fly shop.
My passion for catching fish is eclipsed only by the fish's passion not to be caught.